274 BULLETIN OF THE 



terior extremity. The central plastron is small, triangular, surmounted by 

 an elliptical subanal fasciole. The spines of the lower surface are large 

 and few in number, confined entirely to the edge of the test, leaving broad, 

 bare bands in the ambulaeral areas and adjoining parts, while on the rest of 

 the test the tubercles are minute, carrying small, fine spines, with the ex- 

 ception of three large, curved spines (Lovenia-like) near the circumference, 

 placed in the anterior extremity of the test. The tubercles are also somewhat 

 larger on the edge of the anterior groove, and more closely packed in the pos- 

 terior interambulacral space, from the apex to the anal system, than in re- 

 maining parts of the test. The plates of the two posterior ambulacra are 

 broad, while all the other ambulacra are made up of smaller plates. There 

 are three large genital openings ; the right anterior one is obliterated. The 

 anal system is transversely elliptical, its membrane covered by minute gran- 

 ulation ; an indistinct branch of the subanal fasciole extends along the 

 lower side of the opening ; the anus itself opens in a short, delicate tube, 

 similar to that of Neolampas, but shorter. The whole test is mottled with 

 dark spots; the ground color is grayish, with a purplish tinge. 

 From 320 to 368 fathoms. 



Brissus columbaris Ag., Cat. Rais. 

 Littoral. 



Meoma ventricosa Lutk., Bidrag. 



Syn. Brissus ventricosus Ac, Cat. Rais. 

 " panis Grube, Neue Echin. 

 " spatiosus McCb., P. PI. Foss. S. C, PI. 3, fig. 1. 



Liitken first referred this species to the genus Meoma of Gray, established 

 for a presumed Australian species, M. grandis. Liitken also, in 1863, called 

 my attention to the generic identity of Kleinia nigra A. Ac, with Meoma, 

 which I had with doubt referred to Kleinia. This mistake I was led into 

 by the fact that Gray himself did not refer Brissus ventricosus to Meoma, 

 but still retained it in a section of Brissus. This shows how little reliance 

 can be placed upon the subdivisions which Gray so frequently introduces 

 in his genera (often copied without any attempt at a more accurate discrimi- 

 nation of the species from similar headings in the Catalogue Ilaisonne), 

 when two species as closely allied as Meoma ventricosa and Meoma grandis 

 are placed in two genera, or when in the subdivisions of Echinocardium, as 

 another instance, Echinocardium ovatum is placed in the subdivision of 

 the genus with " deep, odd, ambulaeral groove" instead of being placed in 

 the same subdivision as E. gibbosum. The genus Kleinia I am unable from 

 Gray's figures and descriptions to distinguish from Brissopsis. Meoma grandis 



